Safety alarm system



L. SANTINO SAFETY ALARM SYSTEM Filed Jan. 6, 1953 Dec. 17, 1940.

Patented Dec. 17, 1940 UNITEDv STATES PATENT OFFICE 8 Claims.

This invention relates to safety alarm systems applicable to buildings or enclosures of all types wherein protection is sought against burglary, re, poisonous gases and the like. More specically the invention relates to a radio transmitting safety alarm system provided w-th automatic signalling means. The invention has particular utility in connection with buildings in cities provided with central police and re stations and equipped lo? for the reception of radio signals.

Heretofore in radio alarm signalling systems certain disadvantages have been present such as too great `difficulty of adjustment, lack of positiveness in the operation of the transmitting apparatus, lack of provision for variation in line voltage of the power circuits, lack of adequate equipment to take care of various abnormal disturbances such as that arising from yescaping gas, and other deficiencies.

It is accordingly an object of the present invention to provide a transmitting system whi-ch is positive in its operation, and which automatically restores the apparatus to signalling position should a temporary drop in the line voltage cause an energization of the signalling apparatus; to provide means in a common electrical system for transmitting alarms arising from window or door tampering, or from re; and to provide a novel andr automatic device sensitive to the action of gases for turning on a gas alarm and subsequently restoring itself to condition for taking on new signals. Still another object of the invention is to provide an alarm system which tran-smits signals, indicating Window or door tampering, noiselessly and without Warning tothe building occupants. A further object is the provision of a transmitting system which continues its alarm after the -initial energization until authorized persons, such as the police, arrive to 4o terminate the signal. An object also is to provide a safety alarm system which transmits Voice as well as automatic signals.

Furthe` objects will become apparent on inspection of the following specification describing an arrangement and system whi-ch may be preferred and which is further set forth in the accompanying drawing in which is shown the wiring system and the Various parts including the radio transmitter system, the automatic signal 5o restoring device, the code discv mechanism, the

thermostatic element, and the gas detecting device in diagrammatic perspective, section or plane.

The invention contemplates the use of a radio transmitter electrically connected to a closed circuit system which when `applied to a building includes contacts opened and closed by the movement of windows and doors so that when these elements are opened the closed circuit is broken, thus setting ofi certain automatic code devices which through the transmitter are broadcast 6?' through the central receiving station, the automatic .code indicating the location of the building and the natureof the disturbance, such as burglary in the example mentioned. In the case of fire the closed circuitis opened by a heat re- 1014 sponsive element such as a thermostatic switch or a fuse. In the case of gas the switch is opened by an automatic gas detecting device. In each case mentioned, that is, burglary, iire and ga-s leakage, different code messages are transmitted 1.15: to indicate at the receiving station the type of disturbance at the given location.

In the drawing,

Fig. l is a wiring diagram showing .the signalling unit; and 20'A Fig. 2 is a Wiring diagram showing the contact restoring unit.

Referring to Fig. 1, the power mains are indicated at i and 2 `deriving from -the usual 110 volt alternating current power system between the 25 building meters and fuse box, thus being independent of fuse blowouts. Adaptation to direct currentl may also be made. The power circuit leads through main circuits I0 and II to the transformer I2, the secondary of which connects 30, in series through separable electrical contacts I4 positioned at various windows, doors or other openings of the building in such manner that opening of the windows or doors will cause Idisconnection in the transformer circuit. A master 35 switch I5 short circuits the various window and door contacts I4, this switch being preferably operated by the key of the main or final exit door lock, the action being that when the door is locked the switch I'5 is opened, and when the lock is 40 opened the switch I5 is closed, short circuiting the door and window contacts and permitting free use of the windows and other exits without producing an alarm signal. The circuit I3 including the secondary of transformer. I2 may also include 45 other separable contacts as I6 and Il which are also in series with contacts I4.

The secondary transformer circuit I3 includes in series also the electromagnet I`8 having a metal core I9 projecting at either 50 end as shown. Pivotally positioned adjacent the vends of the electromagnet core I9 are armatures-20 and 2l which are normally held by springs 22 and 2\3 away from the magnet core in'open position. In this displaced position 55 of the armatures 2U and 2| they are adapted to connect with contacts 24 and 25. When armature 2i! engages contact 24 it energizes the motor 3 operating the code device 4 through the gear reduction the power pack 6 and radio transmitter and receiver 1 are also energized. When armature 2| :engages contact 25 it closes the circuit through the code device 4, thu-s energizing the modulating circuits in the transmitter and making eiifective the transmission of the code to the receiving station.

The circuit for energizing the power supply of the transmitter and the motor of the code de vice leads from the wire II through wire 26 to the armature 20, contact 24, wire 21, wire 28I to the motor, wire 29 from the motor, and wire IU to the power main I. Also, from wire 21' the circuit branches through wire 30 to the. transmitter power supply 6 and transmitter 1, returning.

through wire 3| to the outlet main I0.

In the code disc circuit, from the contact 25 of armature 2|, wire 32 connects to the brush 33 onY the rotatable disc 34, the periphery of which is; formed with teeth 35 so as to give the desired sequence of signals indicative of the source of the same. The circuit leads from the brush to the disc to the hub 36 and thence through the hub contact 31, wire 38, code key 39, speech-code switch 4i), the primary of transformer 4I, wire 42, battery 43 to the ground 44. This circuit also includes the secondary of transformer 4I connected at one end to the C battery and at the other to the grid of the modulator tube 45, the plate of which connects to the transformer 46. The secondary of the transformer 46 connects at one end to the high B battery terminal and at the other end tothe amplifying and transmitter unit 1.

The oscillator tube is indicated by the. numeral 52, the plate of which is connected to one side of the primary of the transformer 53, the other side of which is connected to the B-lterminal. The grid circuit of tube 52 connects to one side of the secondary, the other side passing` through the Wire 54 to the armature 2| of the burglar alarm circuit; A wire 55 provided with a switch 56 is connectedacross wires 38 and 54 of the oscillator circuit to short circuit the same when code messages are being transmitted. The oscillator circuit is preferably operable on a thousand cycles and the transmitter on. a wavelength preferably of ten metersand a power output of at least iive watts.

The transmitter is also provided with mechanism to transmit voice, operative through the modulator tube circuit consisting in the voice transmitter 50 which is in the grounded circuit 5I connected to the two-way switch 40. While primarily designed for transmission, the transmitter is also adapted for reception so that signalsor voice may be both sent and received by the apparatus. In the operation of the device for transmission when code messages are being sent, switch 56 of the short circuit 55 is closed, as well as code key 39, and two-Way switch 40 connects the circuit 38 to the circuit of transformer 4|. When voice is to be transmitted switch 40 connects with the` telephonecircuit 5| and short circuiting switch 56 is closed to permit voice transference.

In the operation of the burglar alarm system as hereinabove described, normally the armatures 20 and 2| of electromagnet I8. controlling the burglar alarm circuitare in contact with the core I9 ofthe electromagnet, thereby opening the circuits through contacts 24 and 25. With these contacts open the motor 3 and the transmitter are de-energized and the circuit including the code disc is opened. Should, however, any of the door or window contacts I4, I6 or I1 be opened the electromagnet I8 is de-energized, the springs draw the armatures 20 and 2| away from the magnet core closing the circuits through contacts 24 and 25, thereby energizing the motor 3 and the transmitter and producing code signals through the disc 34 which are immediately transmitted to the receiving station. The signal istransmitted continuously until there is a response on the part of police or other authorized persons who are provided with a key to operate mechanism for moving the armatures 2|) and 2| into engagement with the electromagnet core I9, thereby breaking the alarm circuit. This can be done, however, only after the contacts I4, I6 and I1 are closed so as to provide a closed circuit to the power source. The mechanism for moving the armatures into` Contact with the magnet core will be described hereinafter.

Connected inrparallel to the burglar alarmcircuit' including the electromagnet I8 is'the gas alarm circuit including the electromagnet 66. As shown in the drawing, wire 6I connects one terminal of the secondary of the power transformer I2 tothe electromagnet 63. The other terminal of the electromagnet 60 is connected directly to the gas detecting' device 63, the return circuit 64 of which passes through the hand switch 65 to the other terminal of the secondary of the transformer I2. The gas detecting device 63 is provided with` a casing including a stationary base sectionr 66 and an upper or top movable section 61. The Vbase section 66 may be circular in shape and provided with an annular up-turned ange 68 with an inwardly bent edgeflange 69. The upper casing section 61 is cup shaped, consisting of an upper disc 10 and a lower depending wall 1I provided with an outwardly extending edge flange 12, the latter being adapted to engage the ilange 690i. the base section of the casing on its under side, thereby permitting a limited movement of the upper casing and providing a stop at either end of the path of movement thereof. The casing may be formed of gas permeable substances, and with openings 13 to permit easy ingress of gases into the casing. A perforated box |10 encloses the casing 66 and 61.

Within thecasing and mounted on the base section 66 at approximately the center thereof is an electromagnet 14 which in turn is provided with a movable core 15. The upper end of the core15 is permanently attachedto the under side of the upper disc 10-of the top casing section 61 and is accordingly movable therewith. A spring 16 is interposed between the base of the movable core 15 and the base section 66 for the purpose of holding the armature normally at its upper position with its flange edges 12 contacting against the base section flange 69. The support 11 at the upper end of the electromagnet 14 pivotally carries the spring pressed contact arm 18, the end of which detachablyengages the iixed contact member 19. A depending nger 8U fastened to theunder side of the casing plate 10 directly above the contact arm 18 is adapted to engage the same under certain circumstances, as will hereinafter be pointed out;

Also included within the casing 63 is a gas sensitive element or thermostat 8| consisting of two metal plates 82 and 83 supported on the base section 66. Plate 82` is provided at'its upper end with a contact 84 which is adapted to engage normally the coacting contact member 85. The plates 82 and 83 are of different metaland consequently of different coefficients of heat expansion so that when subjected to heat the contacts 84 and 85 separate, the contacts re-engagng when the temperature of the thermostat is reduced to normal or `room temperature. Any metal may be used provided there is a suilciently marked differenceof heat coeilicient between the two metals; however, I prefer to use brass for plate 82 and iron for plate 83. An adjusting screw 86 is provided for the contact 84 so that A, accommodation for seasonal temperature changes may be made.

Wound around the two Iplates 82 and 83 is a fine coil of wire 81 which is highly absorbent of gases such as illuminating or fuel gases and particularly carbon monoxide, and which in the 20' u traced from the wire 64 to the contact plate 18,

contact'19, wire 88, stationary contact 85, thermostat contact 84 and wire 89 connecting to the wire 62 of electromagnet 60. Forming a bridging connection between wires 62 and 64 is a condenser 90, the purpose of which is to aid in the prevention of spark formations when the contacts of the device separate. Also connected across the wires 62 and 64 in parallel with the contact circuits is the electromagnet 14.

The operation of the gas detector is as' follows: Normally the electromagnet 14 lies in the closed circuit through the electromagnet 60 and the secondary I3 of transformer I2. The degree of energization, however, is weak since the magnet is short circuited by the con-tact circuit and hence i the spring 16 holds the core 15 at the limit of its movement. Should, however, gas leakage occur and penetrate into the casing 63 the palladium wi-re becomes heated, thereby energizing the thermostat 8|, causing Van opening of contacts 84vand 85 and energizing strongly the electromagnet 14.

Thereupon the core 15 movesdownwardly into the electromagnet, bringing down the upper casing 61 until its base flange 12 contacts against the base 66. In this downward movement the finger 80 contacts with the arm 18 breaking the contact at 19. Should the gas now be removed from the vicinity of the detector the thermostat 8| will flex into normal position, restoring electrical connection between contacts 84 and 85. However, the contact between 18 and 19 will still be open since the electromagnet is energized and will continue to be open until some authorized 'person applies a key to open switch 85. Thereupon the core 15 with .its casing armature is released and contacts 18 and 19 are closed so that when switch 65 is again closed the magnet 14 is short circuited by the contact circuit. The device is now in condition for repeating its signal.

When the magnet 14 is initially energized by the breaking of the thermostat contacts 84, 85, circuits are closed to the motorl 3, the code signal device 4, transmitter 1 and the circuit of code wheel 9|. The circuits for accomplishing these results are as follows: Adjacent the core 92 of the electromagnet 60 are two pivoted armatures 93 and 94 normally held from the magnet core by means of springs 95. Armature4 93 in its out position engages stationary contact 96, from this point the circuit passing over wire 91 to wire 21 and then, as' previously indicated in connection with the burglar alarm, to the code motor 3 and the transmitter 1. The pivot point of the armature 93 is connected through the hand switch 98, wire 99 to the wire 26 connecting with the secondary of pofwertransformer |2. This completes a power circuit to the motor and transmitter. Armature 94 engages contact |00 through which the circuit passes by wire to the brush-|02 engaging the toothed periphery of code wheel 9|, the circuit then passing through the hub 36 to thev end contact 31 and thence to the modulator circuit as in the parallel burgl-ar alarm arrangement. The pivot point of anmature 94 is connected through wire |03 to the cir-- cuit 54, passing through the oscillator tube 52 of the transmitter.

As in the case of the burglar alarm, the armatures 93 land 94 are engaged by the core 92 of the magnet 60, thus holding the contacts 96 and |00 open. When the gas detector device, however, functions to open the short circuit the increase of resistance occasioned by the shifting of the current through the electromagnet 14 is sufficient to produce a release of armatures 93 and 94, resulting Ain closing the transmitting and code sending circuits, whereupon, by virtue of the message of the toothed code onthe periphery of wheel 9| there is transmitted signals to the central station, indicating the location of and the presence of gas leakage in the building where the signalling system is located.

My safety alarm system also includes means for notifying a central station of the presence of iire in a building. This re alarm circuit is also connected in parallel to the power trans-former I2V and includes a closed circuit passing through a thermostatic device sensitive to the presence of heat. As in the burglar alarmv and gas detection device, I utilize an electromagnet having a core |06 projecting Ifrom either end and provided with pivoted armatures |01 and |08, each being positioned adjacent opposite ends of the core |06. Springs |09' normally hold these armatures away from the coreand engagement with contacts, armature |01 being adapted to engage contacts |09 and ||0, and armature |08 being adapted to engage contact Movement of these armatures toward the core of the elec-tromagnet separates them from the contacts.

Contact |09 is connected to the motor and transmitter circuit 30 by wire ||2. Contact ||0 passes through the manual switch ||5, electric bell 3 land wire ||4 to the transmitter andmotor circuit 3|. The pivot point of armature |01 is connected through wire I6 to the main wire Contact of armature |08 is' connected through wire ||1 to the brush |8 of code disc 9 and thence to the shaft 36. The pivot point `of armature |08 is connected through wire to the oscillator circuit 54.

The electromagnet |05 is energized by a closed circuit passing through the heat responsive device |2| and including circuit wires |22 and |23 connecting to the secondary of transformer I2. Also, the magnet connects through wire |24 to 'the yother terminal of the secondary of transformer |2, thus completing a normally closed circuit in parallel with the burglar alarm and gas detecting circuits. l

The heat responsive means |2| may be in the nature of a fuse or, as shown, a thermostatic strips.

|30 and |3| a toggle joint.

device comprising two metal strips |25 and |26, preferably of brass and'rnanganese. steel, .having different coeiiicients` of heat expansion when heated by the passage of current through the These strips are mounted as a unit with their nat sides adjacent each-other, one endof the unit being xed on a permanent base and the other end being movable. The free end of the unit carries a contact |21 which is adapted to engage a fixed Contact |28 adjustable by means of the set screw |29. Normally the contacts |21 and |28 are in engagement, but when the strips |25 and |26 are heated by the presence of re at a point nearby, relative expansion of the strips forces the contacts` |21 and |28 apart, thus breaking the closed circuit through the electromagnet and releasing the armatures |01 and. |08. Thereupon the codedisc motor and radio transmitter are energized togetherr with the voscillator circuit from the code Wheel, sending the signal to the receiving station indicating the presence of fire at the location of the signalling apparatus.

In electrical apparatus of the type hereinabove described the possibility constantly exists that due to breakdown in the generating station or'in the transmission lines a temporary failure of the electrical power results. When the line potential in this manner temporarily drops or'is broken, though even for a brief time interval, the various electromagnets of the signallingcircuits become de-energized and the code signals become immediately operative when the line voltage is restored. While the transmission of a triple signal from a building to a central station would, generaly speaking, indicate a breakdown in the signalling apparatus due to the presence of three signals simultaneously, nevertheless such an occurrence is undesirable, involving unnecessary expense and attention. Accordingly, I have devised a mechanismby means of which it is possible automatically to rectify this difculty and restore the various circuits to their original condition after the magnets of the signalling circuits have been de-energized by a temporary break in the line circuit. This mechanism includes means for restoring thel movable armatures of the various electromagnets I8, 60 and |05, but is shown applied to the electromagnet |8 at the lower right hand side of the drawing in Fig. 2. Here it will be observed the electromagnet I8 is shown in perspective with its core |9- adjacent the cooperating armatures and 2|. Pivotally positioned on xed supports adjacent each of the armatures 20 and 2| are arms |30 and |3|. The inner ends of these arms are connected by means of three pivotally connected bars |32, |33 and |34 which yformwith the arms The central bar |33 is provided with an elongated recess or opening |35 in which is seated the flattened end |35 of a rod |31. This rod carries a contact-making arm |38 and the armature |39 of an electromagnet |40. The rod |31 is xedly mounted in relation to the bar |33 and the toggle joint so that when the rod rotates its action is to elongate or retract the toggle and move the arms |30 and |3| either toward the armatures 20 and 2| or away from them. Normally the toggle is open with the weighted portion of the armature |39 helddownwardly by gravity. However, when energized by the electromagnet |40 the armature is moved in relation to the electromagnet, thus rotating the rod |31, lengthening the toggle and-forcing the armatures 20 and 2| into contact with the ends of the electromagnet core I9. Armature |35, as illustrated, has diminished mass in its upper part normallyv adjacentthe electromagnet. This permits the-Lbaseportion` of the armature to act as a pivoting weight andinsure rotation when the armature rotatesto include greater energy from the electromagnet, in accordance with wellknown lawsof magnetism. Rotation of the rod |31-byv thearmature|39 causes movement of the contact-making-arm |38 in a direction to bring spring contact |4| into engagement with fixed contact|421for a purpose hereinafter described. ThisautomaticA signal-restoring mechanism includes also theelectromagnet |43 having an insulated contact |44 on the end of thevcore |45. An armature |46 carrying a contact |41 is positioned so as to permit engagement of contacts |44 and |49. A spring |48 tends to retain armature |46 out ofengagement of the contact |44 and in engagement with contact |49.

Circuitsenergizing the signal restoring mechanism include the wire |50 connected to the main wire |0 and passing through the electromagnet |43 to the junction point |5| where wire |52 connects to the contact |44, and Wire |53 connects to they spring contact |4|. The circuit continues from contact |42 through wire |54 to junction point |55 where one branch leads through wire |56 to the main wire The other branch |51 is connected to the armature |46. From contact |49 connection is made to wire |50 through wire |58, electromagnet |40 and wire The operation of the signal-restoring mechanism may now be described. In the event that the line voltage drops to zero or to an extent that electromagnet IB, for example, releases armatures 20 and 2|, as previously described, circuits will be closed which, as soon as the line voltage is restored, will cause signals to be sent out indicating possible burglary inl the building where the apparatus is installed. Prior to the failure of the line voltage a closed circuit will have been established from the main circuit I0 through wire |50, electromagnet |43, contacts |44 and |41, wires |51 and |50V to the main The circuit through the electromagnet |40 is open and the toggle joint mechanism is also open. When the line voltage drops electromagnet |43 is de-energized, permitting armature |40 to break the circuit through contacts |41 and |44, closing the circuit through contact |49 and the electromagnet |40. When the line voltage is reestablished the shaft |31 is rotated, the toggle arms |30 and |3| restoring the armatures 20 and 2| into engagement with the magnet core |9 and at the same time arm |38 closing the contacts |4| and |42. Closure of these last mentioned contacts permits the ilow of current through-the electromagnet |43 which draws down the armature |46, again restoring the original circuits. There is thus accomplished a complete restoration of the signalling circuits without transmission of signals due to the breakdown of the line voltage.

In order to restore the armatures of the various electromagnets 60, |05, to Contact position against the respective magnet cores, after release during a signal, a toggle mechanism similar to that shown applied to magnet I8 is employed. The shaft |31 has a groove |60 on the armature end adapted to receive a key for manual rotation of the shaft, bringing the arms |30 and |3| against the armatures and moving them back topre-signal position. In the case of magnet I8 a shortcircuit 16| `having a key controlled switch and 2|.l y r Injthe claims the terms primary, secondary and tertiary applied to the circuits indicate f circuit including said electromagnet adaptedwhen the current therein is diminished to permit movement of said armatures to energize the transmitter and device operating means, a source of electric power for said circuits, and second means for moving said armatures, said second means comprisingtlever mechanism for moving said armatures, a movable core attached to said mechanism', a magnet for moving said core, and

, additional 'meansfor energizing said core moving magnet when the voltage of said electric power source diminishes to a point where the armatures are actuated to close the circuits through the transmitter and device operating means.

2. A safety alarm system comprising a transmitter, a signal device, means for operating said device, an electromagnet, armatures for said electromagnet, means for moving said armatures to open and closed positions, circuits closed by 40 the opening of said armatures for energizing said transmitter and device operating means, a circuit including said' electromagnet adapted when the current therein is diminished or broken to permit movement of said armatures to open position to energize the transmitter and device operating means, a switch in said electromagnet circuit, a source of electric power for said circuits, and second means for moving said armatures to closed positions effective after a diminution of voltage of the power source and subsequent opening of the armatures without opening of the electromagnet circuit switch, said second means comprising lever mechanism for moving said armatures, a movable core attached to said mechanism, a magnet for moving said core, and an additional magnet connected in parallel with said core moving magnet adapted for energization for breaking the circuit in the core moving magnet when the voltage of the power source resumes its normal value after diminution in value.

3. In a safety signal system the combination of a transmitter, a device, primary circuits including said transmitter and device, an electric power source connected to said primary circuits, secondary circuits connected to said primary circuits, means in said secondary circuits susceptible to either disconnection or diminution of voltage in the circuits for energizing said primary circuitstertiary circuits, and means in said tertiary circuits eiective to open said primary circuits when the primary circuit is closed through a temporary diminution of current in the secondary circuit without a disconnection of the secondary circuit.

4. In an electrical system, the combination of -a-iirst unit normally` operative for sending-signals', on interruption of a -closed circuit Afand a second unit for making ineffective the signalling function -of- ,said first-unit when the voltage of the power source is temporarily diminished, said iirst unit comprising a transmitter, a signal device, means for operating said device, anl electromagnelt, armatures for 4said electromagnet movable to open and closed positions, means 'for moving said armatures to open position, circuits controlled by said armatures forenergizing said transmitter and device operating meanspa-circuit including said electromagnet adapted-when the current therein is diminished to permit movement of said armatures to energize the trans;

mitter and device operating means, and a source of electricpower for said circuits and said second unit comprising means for moving said armatures t-o closed position whereby the signalling action of the iirst unit is temporarily interrupted.,y

5. In an electrical system,v the combination vof f a iirslt unit normally operative for sending signals on interruption of a-closed circuit and a second unit for preventing operation of the signal sending unit when the voltage of the supply source is temporarily diminished, said first unit comprising a transmitter, a` signal device, means formoperating said device; anelectromagnet, armatures for `said electromagnet movable to open and( closed positions, Ameans for moving said armatures,l

device operating means, a source of electric power for said circuits and said second unit comprising means for moving said armatures to closed position, said means including an electromagnet, a core movable by said electromagnet, and lever mechanism secured Ito said core for mechanically moving said armatures.

6. In a safety alarm system a power source normally operable at a given voltage but susceptible to change decreases of voltage, an electromagnet having a core connected in circuit with said power source, an armature, a signal circuit connected to said armature, the movement of the armature to displaced open position closing said signal circuit, a signal device in said signal circuit, a transmitter connected to the signal device, means for yieldably holding said armature displaced frorn said core, mechanism for moving said armature into contact with said core tobe retained thereby during the energization of the electromagnet, and electrical means eiective only after a drop in the voltage of the power source to a point where the armature is released from the magnet core for operating said mechanism to recontact the armature and core when the voltage of the power source has acquired its normal value after a decrease in value.

7. In a safety alarm system a power source normally operable at a given voltage but susceptible to chance decreases of voltage, an electromagnet having a core connected in circuit with said power source, an armature, a signal circuit connected to said armature, the movement of the armature to displaced open position closing said signal circuit, a signal device in said signal circuit, a transmitter connected to the signal device, means for yieldably holding said armature displaced from said core, mechanism for moving said armature into contact with said core 'circuit `connected to said armature, the movement-'of thearmature'to displaced open position lclosing said signal circuit, a signal device in said tive only after adrop in the Voltage of the power source to apoint where vthe armature is released `from 'the magnet lcorefor operating'said mechanism to re-contact the armature and core when 'the voltage of the'power source has acquired its -normal value after a decrease in value, said electricalmeans including a movable core, a second velectroma'gnet 4adapted to move said movable core, and a third electromagnet, said second signal circuit, a vtransmitter connected to the signal device, means for yieldably holding said armature'displaced from said core, mechanism lincluding lever arms and shaft for moving said armature into contact with said core to be retained thereby during the energization of the electromagnet, and electrical means eiective only vafter a drop in the voltage of the power source to'a point where the armature is released tobe retained thereby duringthe energization `of the electromagnet, and electrical means effecfrom the magnet core for operating said mechanism to recontact the armature and core when the voltage of the power source has acquired its normal value after a decrease in value, said electrical means including a.y movable core,` a second electromagnet adapted to move said movable core, and a third electromagnet, said second and third electromagnets being connected in physical parallel with each other, and switching means for energizing only one of said second and third magnets at a time, said switching means comprising an armature for said third magnet, contacts on either side of, and spaced from, said armature, two normallyopen spring contacts adjacent said arrnaturemechanisrn shaft, a lever armrsecured to the shaft adapted to close said spring contacts when said third magnet armawith one of its contacts and when the line voltage is diminished to release the armature of the vthird electromagnet to close the circuit through the other contact,

second electromagnet and spring contacts whereby the lever mechanism is operated to force the first named armature into contact with the core of the rst electromagnet on the restoration of the line voltage.

LOUIS SANTINO. 

